(noun)when the lights are out, and one male friend swaps in the place of his other male friend who was in the act of coitus with an unassuming young woman, and performs said coitus acts as well; this occurs cyclically between the two men.

Gina, got shitcanned at the box social, and engaged in numerous backshots with Robert. 5 minutes later, Jason showed up and they tagjobbed that meatsleave all night. She never noticed the switch in penises.